Technical Field
The present invention relates to ink, an ink container, and an ink jet recording device.
Description of the Related Art
Ink for use on plain paper and various kinds of coated paper is required to meet the demand for various quality and features and many developments and researches have been made to improve basic quality such as image density. In particular, the demand from the market is strong with regard to improvement on the image density of ink for inkjet on plain paper.
In general, to improve image density, reduction of dynamic surface tension is said to be good. Although static surface tension can be reduced by addition of a small quantity of additives such as fluorosurfactants and silicone-based surfactants, dynamic surface tension thereof is not easily decreased. This is because a surfactant forms a micelle in ink and the micelle is stabilized, so that the surfactant little or never contributes to reduction of dynamic surface tension. In particular, it is difficult to decrease dynamic surface tension by a fluororsurfactant.
In comparison with a fluorosurfactant, a silicone-based surfactant easily decreases dynamic surface tension by controlling molecular structures.
However, when a surfactant to decrease dynamic surface tension is added, static surface tension may be decreased excessively, which leads to making forming meniscus in a nozzle unstable or causing blurring or strike-through on paper.
On the other hand, acetylene glycol-based surfactants are known to reduce dynamic surface tension to a relatively-low level and make the difference between dynamic surface tension and static surface tension small.
Although an acetylene glycol-based surfactant demonstrates good features when the surfactant is used for dye-based ink, the surfactant tends to make dispersion of pigment unstable and cause defective discharging such as nozzle deviation due to agglomeration when the surfactant is used for pigment-dispersion-based ink. In addition, it is also known that ink to which such a surfactant is added tends not to wet-spread well on coated paper and film.